Field of the Disclosure
The present disclosure relates generally to optical communication networks and, more particularly, to low noise colorless, directionless, contentionless reconfigurable optical add/drop multiplexers.
Description of the Related Art
Telecommunication, cable television and data communication systems use optical networks to rapidly convey large amounts of information between remote points. In an optical network, information is conveyed in the form of optical signals through optical fibers. Optical fibers may comprise thin strands of glass capable of communicating the signals over long distances. Optical networks often employ modulation schemes to convey information in the optical signals over the optical fibers. Such modulation schemes may include phase-shift keying (PSK), frequency-shift keying (FSK), amplitude-shift keying (ASK), and quadrature amplitude modulation (QAM).
Optical networks may also include various optical elements, such as amplifiers, dispersion compensators, multiplexer/demultiplexer filters, wavelength selective switches (WSS), optical switches, couplers, etc. to perform various operations within the network. In particular, optical networks may include costly optical-electrical-optical (O-E-O) regeneration at colorless, directionless, contentionless reconfigurable optical add-drop multiplexers (CDC ROADMs) when the reach of an optical signal is limited in a single optical path.
As data rates for optical networks continue to increase, reaching up to 1 terabit/s (1 T) and beyond, the demands on optical signal-to-noise ratios (OSNR) also increase, for example, due to the use of advanced modulation formats, such as QAM and PSK with dual polarization. In particular, noise accumulations resulting from cascading of optical amplifiers in an optical network operating at very high data rates may limit the reach of an optical signal at a desired level of OSNR and may result in an increased number of O-E-O regenerations, which is economically disadvantageous.